根据场景完成对话。

A:What do you think of the question whether students can use cellphones?  

B: ①_______________students  shouldn't use cellphones.  

C: ②  ___________   （恐怕我不能同意你的意见）.I think the cellphone is  helpful to us.  

B: ③   ___________  （我不这样认为）．  

A:Can you give us some reasons?  

B: ④   ___________  （好的）．It does harm to our study. Besides,it will waste our time and money.